1. Field of the Invention
This invention relates to a physiologically-active novel substance "aldostatin", which is an aldose reductase inhibitor, and its salts as well as a production method thereof. Aldostatin, which the present invention provides, is useful for the treatment of certain chronic complications caused by diabetes renalis, such as diabetogenous cataract, retinopathy and neuropathy.
2. Description of the Prior Art
The reduction of blood sugar level has been the subject of a majority of attempts which have heretofore been made to obtain antidiabetic drugs. Under the circumstances, almost no means is however known for the prevention or reduction of chronic diabetogenous complications such as diabetogenous cataract, retinopathy and neuropathy. According to Sakamoto et al. ["Pharmacia" 19, 43, (1983)], the metabolism in the polyol system is activated by slight sthenia of an aldose reductase in a state of high blood sugar level such as diabetic, resulting in further promotion of the abnormal accumulation of sorbitol, galactitol and fructose. These sorbitol, galactitol and fructose are relatively stable in cells. Once they are formed there, their transit to the outside of the cells is scarcely observed. This disturbance to the balanced production and excretion leads to the intracellular accumulation of such sugar alcohols. This is in turn considered to cause accumulation of water in cells so that the cells can no longer maintain their normal function, resulting in a histionic problem. It has hence been considered that the abnormal intracellular accumulation of sorbitol, galactitol and fructose can be avoided and the cellular function can be maintained normal if the activities of the aldose reductase are inhibited.
Accordingly, there has been a long-standing demand for the provision of a novel aldose reductase inhibitor useful for the prevention or treatment of chronic diabetogenous complications.